Breast cancer is the second largest cancer killer of North American women. There is good evidence that earlier detection can reduce mortality, and x- ray mammography is currently the most sensitive non-invasive means of breast cancer detection. Conventional mammography, using a film-screen imaging system, is limited in terms of its contrast, latitude and noise properties, and because of this, subtle cancers may be missed. Digital mammography could allow these difficulties to be overcome providing more sensitivity of detection of subtle soft tissue masses and microcalcifications, both important radiologic signs of breast caner. In the proposed research, a digital mammographic imaging system will be constructed, whose design is based on the previous and current work of the applicants. The system will employ solid state detector technology, developed in this laboratory to allow accurate acquisition of the mammographic image over a wide range of x-ray intensities and at very high spatial resolution (0.05 mm picture elements). After physical characterization of the performance of the system in the laboratory, using standard test procedures, as well as a new anthropomorphic breast phantom developed here, the system will be sent to the Breast Imaging Center at Thomas Jefferson University Hospital where its performance for detection of breast cancer will be compared with state-of-the-art film-screen mammography by means of observer performance evaluation and also in terms of sensitivity and specificity of cancer detection. Continuing laboratory research will focus on refinement and optimization of the imaging system and exploration of new techniques made possible with a digital imaging system e.g., improvement of imaging in the very dense breast, imaging of breasts containing silicone implants and improved diagnosis of benign vs malignant breast disease with dual energy mammography and iodine contrast digital subtraction mammography. The applicants will also provide coordination of a National Digital Mammography Development Group of seven synergistic research efforts in: clinical evaluation of digital mammography, image processing, continued development of high resolution detectors for mammography, computer-aided diagnosis and telemammography.